One of the (now) distinctive features of the Ambrosian rite is the "uncapped" thurible -- a thurible, or censer, without the decorative top (or cap) that covers the burning coals and incense within. Here is an example of just such a thurible taken from within the context of Ambrosian rite liturgy:
By way of comparison, here is a the "capped" version of the thurible that most of us are now familiar with:
While this distinction may seem unique to the Ambrosian rite (and it is indeed so within contemporary times), in actuality, like many things in the Ambrosian rite, it is simply an older form of a more ancient model that the Ambrosian rite has managed to preserve.
Here, for example, is this same uncapped form of the thurible as seen in one of the mosaics of San Vitale in Ravenna which would not come within the context of the Ambrosian rite:
